Schedule of Summary of Derivative Hedges (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Feb. 28, 2014
Derivatives Not Designated As Hedging Instruments | Commodity Contracts
Derivative [Line Items]
Notional Amount	$ 24,330
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Minimum
Derivative [Line Items]
Maturity Date(s)	2014-03
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Maximum
Derivative [Line Items]
Maturity Date(s)	2015-12
Derivatives Not Designated As Hedging Instruments | Foreign Currency Contracts
Derivative [Line Items]
Notional Amount	10,000
Maturity Date(s)	2014-05
Cash Flow Hedges | Commodity Contracts
Derivative [Line Items]
Notional Amount	28,265
Cash Flow Hedges | Commodity Contracts | Minimum
Derivative [Line Items]
Maturity Date(s)	2014-03
Cash Flow Hedges | Commodity Contracts | Maximum
Derivative [Line Items]
Maturity Date(s)	2014-12
Cash Flow Hedges | Interest Rate Contracts
Derivative [Line Items]
Notional Amount	$ 100,000
Cash Flow Hedges | Interest Rate Contracts | Minimum
Derivative [Line Items]
Maturity Date(s)	2014-06
Cash Flow Hedges | Interest Rate Contracts | Maximum
Derivative [Line Items]
Maturity Date(s)	2014-12